Relative abundance of Legionella ASVs, according to spring cluster and collection dates. Legionella ASVs were pre-filtered to a minimum frequency of 20 (top panel) or 2000 (bottom panel) reads. Samples are ordered by date, faceted vertically by spring cluster and horizontally by water and biofilm. As numerous ASVs (1073) were included in the construction of each barplot, colors are repetitive and are not indicative of specific ASVs. The identity of the most abundant ASVs is presented in Fig. 4 a,b and Supplementary Data 4 . White barplots indicate Legionella ASVs were not detected. Biofilm sampling was not possible for Tiberias Pump, Haon borehole, and Barbutim stations. For Nur station, only biofilm from September 2017 was available.
